• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Modulating the Bonding Properties of N-Heterocyclic Carbenes (NHCs): A Systematic Charge-Displacement Analysis
【24h】

Modulating the Bonding Properties of N-Heterocyclic Carbenes (NHCs): A Systematic Charge-Displacement Analysis

机译：调节N-杂环碳凝胶（NHC）的粘合性能：系统电荷 - 位移分析

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In view of their intensive use as ligands in many reactions catalyzed by transition-metal complexes, modulation of the bonding properties of N-heterocyclic carbenes (NHCs) on a rational basis is highly desirable, which should enable optimization of current applications or even promote new functions. In this paper, we provide a quantitative analysis of the chemical bond between a metal fragment AuCl and a series of 29 different NHCs in [(NHC)AuCl] complexes. NHCs electronic properties are modified through: i) variation of the groups attached to the NHC nitrogen atoms or backbone; ii) change of unsaturation/size of the NHC ring; iii) inclusion of paracyclophane moieties; or iv) heteroatom substitution on the NHC ring. For evaluating the donation and back-donation components of the Dewar–Chatt–Duncanson (DCD) model in the NHC-AuCl bond, we apply the chargedisplacement (CD) analysis within the NOCV (natural orbitals for chemical valence) framework, a methodology that avoids the constraint of using symmetrized structures. We show that modulation of the NHC bonding properties requires substantial modification of their structure, such as, for instance, insertion of two ketone groups into the NHC backbone (which enhances the π back-donation bond component and introduces an effective electronic communication within the NHC ring) or replacement of a nitrogen atom in the ring with an sp~3 or sp~2 carbon atom (which increases and decreases the p back-donation bond component, respectively). We extend our investigation by quantitatively comparing the NHC electronic structures for a subset of 13 NHCs in [(NHC)PPh] adducts, the ~(31)P NMR chemical shift values of which are experimentally available. The latter have been considered as a suitable tool for measuring the NHCs p acceptor properties [Bertrand et al., Angew. Chem. Int. Ed. 2013, 52, 2939–2943] . We show that information obtained using the metal fragment can be transferred to the PPh moiety and vice versa. However, the
机译：鉴于其密集用作通过过渡金属配合物催化的许多反应中的配体，对N-杂环碳碳（NHC）的键合性能的调节是非常理性的，这应该能够实现当前应用的优化甚至促进新的应用职能。在本文中，我们在[（NHC）AuCl]配合物中提供了金属片段AuCl和一系列29种不同NHC之间的化学键的定量分析。 NHCS电子性质通过：I）附着在NHC氮原子或骨架上的基团的变化; ii）改变NHC环的不饱和度/大小; iii）包含定义的部分;或iv）杂原子取代在NHC环上。为了评估NHC-AUCL键在NHC-AUCL键中的德惠 - Chatt-Duncanson（DCD）模型的捐赠和后捐赠组分，我们在NOCV（化学价值的天然轨道）框架内应用了加密剥离量（CD）分析，这是一种方法避免使用对称结构的约束。我们表明，NHC键合性的调节需要大量改性它们的结构，例如，将两个酮基插入NHC骨架（这增强了π背部捐赠键组件，并在NHC内引入有效的电子通信。环）或用SP〜3或SP〜2碳原子（分别增加并降低P反向捐赠键组分）的环中置换氮原子。我们通过定量比较[（NHC）PPH]加合物中的13个NHC的子集NHC电子结构来延长我们的研究，其〜（31）P NMR化学位移值是通过实验可用的。后者被认为是用于测量NHCS P受体特性的合适工具[Bertrand等，Angew。化学。 int。编辑。 2013,52,2939-2943]。我们表明使用金属片段获得的信息可以转移到PPH部分中，反之亦然。然而

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号